A chip and wafer coaxial alignment device, thermal compression bonding apparatus and method

Abstract

This invention relates to the field of semiconductor thermocompression bonding technology, specifically to a coaxial alignment device, thermocompression bonding equipment, and method for chips and wafers. To address the problem of low alignment accuracy between chips and wafers in existing technologies, this invention provides a novel coaxial alignment device for chips and wafers, comprising a heat-insulating housing suspended on a three-axis moving platform. The heat-insulating housing includes a first camera, a first lens group, a first light source, a first horizontal beam splitter, a second lens group, a second camera, a third lens group, a second light source, a second horizontal beam splitter, a fourth lens group, and a vertical beam splitter. The heat-insulating housing has an upper window and a lower window. This invention designs a coaxial alignment device for chips and wafers and places it between the chip and the wafer. Through the ingenious design of the upper and lower optical paths, real-time acquisition of chip and wafer images is achieved, realizing high-precision coaxial alignment between the chip and the wafer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor thermo-press bonding technology, specifically to a coaxial alignment device for a chip and a wafer, thermo-press bonding equipment, and method. Background Technology

[0002] Thermocompression bonding is one of the mainstream advanced packaging technologies in the semiconductor industry. Its core principle is to achieve a strong connection between materials by applying temperature and pressure, providing stable and reliable electrical and mechanical connections for semiconductor devices. Thermocompression bonding is widely used in high-end manufacturing fields such as integrated circuits, microelectronics, and optoelectronics, and is particularly suitable for high-end chip mass production scenarios that require high-precision and high-reliability packaging.

[0003] The thermocompression bonding process between a chip and a wafer is as follows: First, the wafer is placed on a heating stage and continuously heated to maintain a constant temperature. Simultaneously, a bonding head located above the heating stage picks up the chip from a transfer stage and moves to the wafer bonding position to align the chip with the wafer. After alignment, the bonding head moves along the Z-axis to the bonding height and completes the bonding according to the set fixed temperature and pressure, ultimately completing the thermocompression bonding between the chip and the wafer. The alignment of the chip and wafer is a critical step in thermocompression bonding, and its accuracy directly affects the final bonding quality. Furthermore, since the radius of the bonding pillar is only about 5µm, even a tiny alignment deviation can cause a bridge short circuit, leading to permanent chip damage. Therefore, to ensure the quality of the thermocompression bonding between the chip and the wafer, the alignment accuracy must be guaranteed.

[0004] Traditional chip-wafer alignment primarily relies on a top-view camera mounted on the bonding head. The alignment is achieved by calibrating the positional relationship between the camera and the bonding head. First, the camera captures the alignment position of the chip and wafer, recording the wafer bonding location information. Then, based on this information and the previously calibrated relationship, the bonding head is moved to the alignment position for thermo-bonding. However, this alignment method heavily depends on the accuracy of the calibration of the camera-bonding head's position and the head's movement precision, resulting in relatively low alignment accuracy. Furthermore, during chip-wafer alignment, the wafer is continuously heated, and its internal thermal environment affects the imaging accuracy of the camera, further impacting the chip-wafer alignment accuracy. Summary of the Invention

[0005] In order to solve the problem of low alignment accuracy between chips and wafers in the prior art, the present invention provides a new coaxial alignment device, thermosetting bonding equipment and method for chips and wafers.

[0006] This invention is achieved using the following technical solution:

[0007] A coaxial alignment device for a chip and a wafer includes a heat-insulating housing suspended on a three-axis moving platform. The heat-insulating housing includes a first camera, a first lens group, a first light source, a first horizontal beam splitter, a second lens group, a second camera, a third lens group, a second light source, a second horizontal beam splitter, a fourth lens group, and a vertical beam splitter, all arranged on the same horizontal plane. The first light source and the second light source are coaxially arranged. The top and bottom of the heat-insulating housing are respectively provided with an upper window and a lower window.

[0008] The first light source passes through the first horizontal beam splitter, the first lens group, and the vertical beam splitter before shining onto the chip through the upper window of the heat insulation housing. The reflected light from the chip returns and passes through the upper window of the heat insulation housing, the vertical beam splitter, and the first lens group before being reflected and deflected by 90° at the first horizontal beam splitter. Then, it passes through the second lens group and enters the first camera, forming the upper optical path and completing the chip imaging.

[0009] The second light source, after passing through the second horizontal beam splitter, the third lens group, and the vertical beam splitter, illuminates the wafer through the lower window of the heat insulation housing. The emitted light from the wafer returns through the lower window of the heat insulation housing, the vertical beam splitter, and the third lens group, and is reflected and deflected by 90° at the second horizontal beam splitter. Then, it enters the second camera through the fourth lens group, forming the lower optical path and completing the wafer imaging.

[0010] Principle Analysis: This application constructs a type of vertically symmetrical dual-optical-path coaxial imaging structure by setting a first horizontal beamsplitter, a second horizontal beamsplitter, and a vertical beamsplitter. Simultaneously, the collaborative optical architecture of the three beamsplitters not only simplifies the system layout but also improves the system's space utilization and stability, significantly enhancing the alignment accuracy and repeatability of the chip and wafer. Specifically, the first and second light sources provide illumination for the chip and wafer, respectively; the first and third lens groups are used for coaxial focusing illumination of the chip and wafer, respectively. The reflected light from the chip and wafer re-enters the third lens group. The first and third lens groups generate collimated light; the second and fourth lens groups are used for magnification and pixel correction of the imaging optical path; the first and second horizontal beam splitters are used to separate the illumination and imaging optical paths; the vertical beam splitter is used to merge the upper and lower beams onto the same optical axis to ensure that the alignment reference between the chip and the wafer is consistent; in addition, since the heating stage used to place the wafer is always under continuous heating, the thermal environment it creates will affect the imaging accuracy of the optical devices and the two cameras, so a heat-insulating housing is required to ensure the alignment accuracy between the chip and the wafer.

[0011] Furthermore, heat-insulating glass is installed at both the upper and lower windows of the heat-insulating shell to further reduce the impact of heat radiation without affecting the light path.

[0012] Furthermore, the heat insulation shell is a double-layer shell structure consisting of a heat insulation cover and an inner shell. The heat insulation cover is made of stainless steel and performs preliminary heat insulation treatment to initially reduce the temperature.

[0013] Furthermore, a heat insulation film is provided on the inner surface of the inner housing to further prevent the optical components and camera inside the heat insulation housing from being affected by high temperatures, thus ensuring the alignment accuracy of the chip and the wafer.

[0014] Furthermore, air-cooled plates are installed on the outer sides of the inner casing as active heat dissipation devices. Through gas circulation, heat is carried away and the temperature of the inner casing is reduced, further ensuring the alignment accuracy between the chip and the wafer.

[0015] Furthermore, multiple temperature sensors are installed on the inner wall of the heat shield to facilitate monitoring of the internal temperature and ensure the alignment accuracy of the chip and the wafer.

[0016] A thermocompression bonding device for chips and wafers includes a bonding head, a heating stage in the center for placing the wafer, a coaxial alignment device, and a host computer. The bonding head and the heating stage are arranged vertically, and the coaxial alignment device is located between the heating stage and the bonding head.

[0017] The coaxial alignment device includes a heat-insulated housing suspended on a three-axis moving platform. The heat-insulated housing includes a first camera, a first lens group, a first light source, a first horizontal beam splitter, a second lens group, a second camera, a third lens group, a second light source, a second horizontal beam splitter, a fourth lens group, and a vertical beam splitter, all arranged on the same horizontal plane. The first light source and the second light source are arranged coaxially. The top and bottom of the heat-insulated housing are respectively provided with an upper window and a lower window.

[0018] The first light source, after passing through the first horizontal beam splitter, the first lens group, and the vertical beam splitter, illuminates the chip through the upper window of the heat insulation housing. The reflected light from the chip returns and passes through the upper window of the heat insulation housing, the vertical beam splitter, and the first lens group, where it is reflected and deflected by 90° at the first horizontal beam splitter. Then, it enters the first camera through the second lens group, forming the upper optical path and obtaining the chip image.

[0019] The second light source, after passing through the second horizontal beam splitter, the third lens group, and the vertical beam splitter, illuminates the wafer through the lower window of the heat insulation housing. The emitted light from the wafer returns and passes through the lower window of the heat insulation housing, the vertical beam splitter, and the third lens group, where it is reflected and deflected by 90° at the second horizontal beam splitter. Then, it enters the second camera through the fourth lens group, forming the lower optical path to obtain the wafer image.

[0020] The host computer is used to control the welding head to pick up the chip, control the movement of the welding head, and control the movement of the three-axis moving platform. At the same time, the host computer receives chip images and wafer images transmitted by the first and second cameras in real time, calculates the pixel position deviation between the chip image and the wafer image, and controls the movement of the welding head based on the calculated pixel position deviation between the chip image and the wafer image.

[0021] Furthermore, heat-insulating glass is installed at both the upper and lower windows of the heat-insulating shell to further reduce the impact of heat radiation without affecting the light path.

[0022] Furthermore, the heat insulation shell is a double-layer shell structure consisting of a heat insulation cover and an inner shell. The heat insulation cover is made of stainless steel and performs preliminary heat insulation treatment to initially reduce the temperature.

[0023] The method for thermocompression bonding of chips and wafers using the above-mentioned equipment includes the following steps: 1) placing the wafer in the center of the heating stage; 2) the host computer controls the welding head to pick up the chip and move it to the pre-aligned position with the wafer; 3) the host computer controls the three-axis moving platform to position the coaxial alignment device between the heating stage and the welding head; 4) turning on the first light source and the second light source to obtain chip images and wafer images through the upper and lower optical paths, respectively; 5) uploading the obtained chip images and wafer images to the host computer, which calculates the pixel position deviation between the chip image and the wafer image, and adjusts the position of the welding head in real time according to the calculated pixel position deviation until the pixel position deviation between the chip image and the wafer image is zero, thus completing the chip-wafer alignment; 6) the host computer controls the welding head to move to the welding height and then performs the welding process to complete the thermocompression bonding of the chip and wafer.

[0024] The beneficial effects of this invention are as follows: This invention designs a coaxial alignment device for chips and wafers and places it between the chip and the wafer. Through the ingenious design of the upper and lower optical paths, real-time acquisition of chip and wafer images is achieved. Simultaneously, based on the calculated pixel position deviation between the chip image and the wafer image, high-precision coaxial alignment of the chip and wafer is realized, ensuring the quality of thermocompression bonding between the chip and the wafer. Furthermore, the coaxial alignment device for chips and wafers described in this invention has a compact structure and high integration, making it easy to embed into existing bonding equipment. It also possesses multi-size compatibility and process adaptability, supporting various bonding materials and advanced packaging processes. In addition, the thermocompression bonding equipment described in this invention also has real-time monitoring and closed-loop control capabilities, which can dynamically compensate for alignment deviations, improve process stability and production efficiency, and reduce reliance on manual intervention and overall manufacturing costs. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the coaxial alignment device for chips and wafers described in this invention.

[0028] In the diagram: 1-First light source, 2-First horizontal beam splitter, 3-First lens group, 4-Vertical beam splitter, 5-Second lens group, 6-First camera, 7-Second light source, 8-Second horizontal beam splitter, 9-Third lens group, 10-Fourth lens group, 11-Second camera. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0031] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] like Figure 1 As shown, a coaxial alignment device for a chip and a wafer includes a heat-insulating housing suspended on a three-axis moving platform. The heat-insulating housing includes a first camera 6, a first lens group 3, a first light source 1, a first horizontal beam splitter 2, a second lens group 5, a second camera 11, a third lens group 9, a second light source 7, a second horizontal beam splitter 8, a fourth lens group 10, and a vertical beam splitter 4, all arranged on the same horizontal plane. The first light source 1 and the second light source 7 are coaxially arranged. The top and bottom of the heat-insulating housing are respectively provided with an upper window and a lower window.

[0033] The first light source 1, after passing through the first horizontal beam splitter 2, the first lens group 3, and the vertical beam splitter 4, illuminates the chip through the upper window of the heat insulation housing. The reflected light from the chip returns and passes through the upper window of the heat insulation housing, the vertical beam splitter 4, and the first lens group 3, where it is reflected and deflected by 90° at the first horizontal beam splitter 2. Then, it enters the first camera 6 through the second lens group 5, forming the upper optical path and completing the chip imaging.

[0034] The second light source 7, after passing through the second horizontal beam splitter 8, the third lens group 9, and the vertical beam splitter 4, illuminates the wafer through the lower window of the heat insulation housing. The emitted light from the wafer returns through the lower window of the heat insulation housing, the vertical beam splitter 4, and the third lens group 9, and is reflected and deflected by 90° at the second horizontal beam splitter 8. Then, it enters the second camera 11 through the fourth lens group 10, forming the lower optical path and completing the wafer imaging.

[0035] Principle: This application constructs a type of vertically symmetrical dual-optical-path coaxial imaging structure by setting a first horizontal beamsplitter 2, a second horizontal beamsplitter 8, and a vertical beamsplitter 4. Simultaneously, the collaborative optical architecture of the three beamsplitters not only simplifies the system layout but also improves the system's space utilization and stability, significantly enhancing the alignment accuracy and repeatability of the chip and wafer. Specifically, the first light source 1 and the second light source 7 provide illumination for the chip and wafer, respectively; the first lens group 3 and the third lens group 9 provide coaxial focusing illumination for the chip and wafer, respectively. The reflected light from the chip and wafer re-enters the first lens group. The collimated light is generated after lens group 3 and the third lens group 9; the second lens group 5 and the fourth lens group 10 are used for magnification and pixel correction of the imaging optical path; the first horizontal beam splitter 2 and the second horizontal beam splitter 8 are used to separate the illumination optical path and the imaging optical path; the vertical beam splitter 4 is used to merge the upper and lower beams to the same optical axis to ensure that the alignment reference of the chip and the wafer is consistent; in addition, since the heating stage used to place the wafer is always in a continuous heating process, the thermal field environment it forms will affect the imaging accuracy of the optical devices and the two cameras, so a heat insulation shell is required to ensure the alignment accuracy of the chip and the wafer.

[0036] In practice, heat-insulating glass is installed at both the upper and lower windows of the heat-insulating shell to further reduce the impact of heat radiation without affecting the light path.

[0037] In practice, the heat insulation shell is a double-layer shell structure consisting of a heat insulation cover and an inner shell. The heat insulation cover is made of stainless steel and performs preliminary heat insulation treatment to initially reduce the temperature.

[0038] In practice, a heat insulation film is provided on the inner surface of the inner shell to further prevent the optical components and camera inside the heat insulation shell from being affected by high temperature, and to ensure the alignment accuracy of the chip and the wafer.

[0039] In practice, air-cooled plates are installed on the outer sides of the inner casing as active heat dissipation devices. Through gas circulation, heat is carried away, reducing the temperature of the inner casing and further ensuring the alignment accuracy between the chip and the wafer.

[0040] In this specific embodiment, multiple temperature sensors are installed on the inner wall of the heat insulation cover to facilitate monitoring of the internal temperature and ensure the alignment accuracy of the chip and the wafer.

[0041] A thermocompression bonding device for chips and wafers includes a bonding head, a heating stage in the center for placing the wafer, a coaxial alignment device, and a host computer. The bonding head and the heating stage are arranged vertically, and the coaxial alignment device is located between the heating stage and the bonding head.

[0042] The coaxial alignment device includes a heat-insulating shell suspended on a three-axis moving platform. The heat-insulating shell includes a first camera 6, a first lens group 3, a first light source 1, a first horizontal beam splitter 2, a second lens group 5, a second camera 11, a third lens group 9, a second light source 7, a second horizontal beam splitter 8, a fourth lens group 10, and a vertical beam splitter 4, all arranged on the same horizontal plane. The first light source 1 and the second light source 7 are arranged coaxially. The top and bottom of the heat-insulating shell are respectively provided with an upper window and a lower window.

[0043] The first light source 1, after passing through the first horizontal beam splitter 2, the first lens group 3, and the vertical beam splitter 4, illuminates the chip through the upper window of the heat insulation housing. The reflected light from the chip returns and passes through the upper window of the heat insulation housing, the vertical beam splitter 4, and the first lens group 3, where it is reflected and deflected by 90° at the first horizontal beam splitter 2. Then, it enters the first camera 6 through the second lens group 5, forming the upper optical path and obtaining the chip image.

[0044] The second light source 7, after passing through the second horizontal beam splitter 8, the third lens group 9, and the vertical beam splitter 4, illuminates the wafer through the lower window of the heat insulation housing. The emitted light from the wafer returns through the lower window of the heat insulation housing, the vertical beam splitter 4, and the third lens group 9, and is reflected and deflected by 90° at the second horizontal beam splitter 8. Then, it enters the second camera 11 through the fourth lens group 10, forming the lower optical path and obtaining the wafer image.

[0045] The host computer is used to control the welding head to pick up the chip, control the movement of the welding head, and control the movement of the three-axis moving platform. At the same time, the host computer receives chip images and wafer images transmitted by the first camera 6 and the second camera 11 in real time, calculates the pixel position deviation between the chip image and the wafer image, and controls the movement of the welding head according to the calculated pixel position deviation between the chip image and the wafer image.

[0046] In practice, heat-insulating glass is installed at both the upper and lower windows of the heat-insulating shell to further reduce the impact of heat radiation without affecting the light path.

[0047] In practice, the heat insulation shell is a double-layer shell structure consisting of a heat insulation cover and an inner shell. The heat insulation cover is made of stainless steel and performs preliminary heat insulation treatment to initially reduce the temperature.

[0048] The method for thermocompression bonding of chips and wafers using the above-mentioned equipment includes the following steps: 1) placing the wafer in the center of the heating stage; 2) the host computer controls the welding head to pick up the chip and moves it to the pre-aligned position with the wafer; 3) the host computer controls the three-axis moving platform to position the coaxial alignment device between the heating stage and the welding head; 4) turning on the first light source 1 and the second light source 7 to obtain chip images and wafer images through the upper and lower optical paths, respectively; 5) uploading the obtained chip images and wafer images to the host computer, which calculates the pixel position deviation between the chip image and the wafer image, and adjusts the position of the welding head in real time according to the calculated pixel position deviation until the pixel position deviation between the chip image and the wafer image is zero, thus completing the chip-wafer alignment; 6) the host computer controls the welding head to move to the welding height and then performs the welding process to complete the thermocompression bonding of the chip and wafer.

[0049] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A coaxial alignment device for a chip and a wafer, characterized in that, The device includes a heat-insulating shell suspended on a three-axis moving platform. The heat-insulating shell contains a first camera (6), a first lens group (3), a first light source (1), a first horizontal beam splitter (2), a second lens group (5), a second camera (11), a third lens group (9), a second light source (7), a second horizontal beam splitter (8), a fourth lens group (10), and a vertical beam splitter (4), all arranged on the same horizontal plane. The first light source (1) and the second light source (7) are arranged coaxially. The top and bottom of the heat-insulating shell are respectively provided with an upper window and a lower window. Heat-insulating glass is provided at both the upper window and the lower window of the heat-insulating shell. The first light source (1) passes through the first horizontal beam splitter (2), the first lens group (3), and the vertical beam splitter (4) before shining onto the chip through the upper window of the heat insulation housing. The reflected light from the chip returns through the upper window of the heat insulation housing, the vertical beam splitter (4), and the first lens group (3), and is deflected by 90° at the first horizontal beam splitter (2). Then, it passes through the second lens group (5) and enters the first camera (6) to form the upper optical path and complete the chip imaging. The second light source (7) passes through the second horizontal beam splitter (8), the third lens group (9), and the vertical beam splitter (4) before illuminating the wafer through the lower window of the heat insulation housing. The emitted light from the wafer returns through the lower window of the heat insulation housing, the vertical beam splitter (4), and the third lens group (9), and is reflected and deflected by 90° at the second horizontal beam splitter (8). Then, it passes through the fourth lens group (10) and enters the second camera (11) to form the lower optical path and complete the wafer imaging.

2. The coaxial alignment device for a chip and a wafer according to claim 1, characterized in that, The heat insulation shell is a double-layer shell structure consisting of a heat insulation cover and an inner shell. The heat insulation cover is made of stainless steel.

3. The coaxial alignment device for a chip and a wafer according to claim 2, characterized in that, The inner surface of the inner shell is provided with a heat insulation film.

4. The coaxial alignment device for a chip and a wafer according to claim 3, characterized in that, Air-cooled plates are installed on the outer sides of the inner shell.

5. The coaxial alignment device for a chip and a wafer according to claim 4, characterized in that, Multiple temperature sensors are installed on the inner wall of the heat insulation cover.

6. A thermoforming device for bonding chips and wafers, characterized in that, It includes a welding head, a heating stage in the center for placing the wafer, a coaxial alignment device, and a host computer. The welding head and the heating stage are arranged vertically, and the coaxial alignment device is located between the heating stage and the welding head. The coaxial alignment device includes a heat-insulating shell suspended on a three-axis moving platform. The heat-insulating shell includes a first camera (6), a first lens group (3), a first light source (1), a first horizontal beam splitter (2), a second lens group (5), a second camera (11), a third lens group (9), a second light source (7), a second horizontal beam splitter (8), a fourth lens group (10), and a vertical beam splitter (4), all arranged on the same horizontal plane. The first light source (1) and the second light source (7) are arranged coaxially. The top and bottom of the heat-insulating shell are respectively provided with an upper window and a lower window. The first light source (1) passes through the first horizontal beam splitter (2), the first lens group (3), and the vertical beam splitter (4) before shining onto the chip through the upper window of the heat insulation housing. The reflected light from the chip returns through the upper window of the heat insulation housing, the vertical beam splitter (4), and the first lens group (3), and is deflected by 90° at the first horizontal beam splitter (2). Then, it passes through the second lens group (5) and enters the first camera (6) to form the upper optical path and obtain the chip image. The second light source (7) passes through the second horizontal beam splitter (8), the third lens group (9), and the vertical beam splitter (4) before illuminating the wafer through the lower window of the heat insulation housing. The emitted light from the wafer returns through the lower window of the heat insulation housing, the vertical beam splitter (4), and the third lens group (9), and is reflected and deflected by 90° at the second horizontal beam splitter (8). Then, it passes through the fourth lens group (10) and enters the second camera (11) to form the lower optical path and obtain the wafer image. The host computer is used to control the welding head to pick up the chip, control the movement of the welding head, and control the movement of the three-axis moving platform. At the same time, the host computer receives the chip image and wafer image transmitted by the first camera (6) and the second camera (11) in real time, calculates the pixel position deviation between the chip image and the wafer image, and controls the movement of the welding head according to the calculated pixel position deviation between the chip image and the wafer image.

7. The hot-press bonding apparatus for chips and wafers according to claim 6, characterized in that, Insulated glass is installed at both the upper and lower windows of the insulated housing.

8. The hot-press bonding apparatus for chips and wafers according to claim 7, characterized in that, The heat insulation shell is a double-layer shell structure consisting of a heat insulation cover and an inner shell. The heat insulation cover is made of stainless steel.

9. A method for thermally bonding a chip to a wafer using a thermal bonding apparatus as described in claim 6, 7, or 8, characterized in that, The steps include: 1) placing the wafer in the center of the heating stage; 2) the host computer controls the welding head to pick up the chip and controls the welding head to move to the pre-aligned position with the wafer; 3) the host computer controls the three-axis moving platform so that the coaxial alignment device is located between the heating stage and the welding head; 4) the first light source (1) and the second light source (7) are turned on, and the chip image and wafer image are obtained through the upper optical path and the lower optical path respectively; 5) Upload the obtained chip image and wafer image to the host computer. The host computer calculates the pixel position deviation between the chip image and the wafer image, and adjusts the position of the welding head in real time according to the calculated pixel position deviation between the chip image and the wafer image until the pixel position deviation between the chip image and the wafer image is zero, thus completing the chip and wafer alignment. 6) After the host computer controls the welding head to move to the welding height, the welding process is carried out to complete the thermo-press bonding of the chip and the wafer.

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